System and method for transporting digital baseband streams in a network environment

ABSTRACT

A method is provided in example embodiments that include receiving a radio signal stream and segmenting the radio signal stream into segments. The segments may be packetized and transported in packets over a pseudowire in a packet-switched network. The radio signal stream can be reconstructed from the segments. In more particular embodiments, the pseudowire may be a multi-protocol label switching pseudowire or a layer 2 tunneling protocol pseudowire, for example. In yet other specific example embodiments, the radio signal stream may be received using a common public radio interface or a femtocell application programming interface.

TECHNICAL FIELD

This disclosure relates in general to the field of communications and,more particularly, to a system and a method for transporting digitalbaseband data streams in a network environment.

BACKGROUND

Networking architectures have grown increasingly complex incommunications environments, particularly mobile wireless environments.Network service providers also continue to steadily increasing theirwireless service offerings to provide better coverage of specializedspaces. This includes the deployment and integration of WiMAX, WiFi,metrocells, microcells, picocells, and femtocells, for example, whichcan be linked to backhaul networks. However, many challenges remain inintegrating fronthaul communications with backhaul networks: some ofthese challenges may include cost reduction, maintainability, andtechnological interworking.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present disclosure andfeatures and advantages thereof, reference is made to the followingdescription, taken in conjunction with the accompanying figures, whereinlike reference numerals represent like parts, in which:

FIG. 1 is a simplified block diagram illustrating an example embodimentof a communication system in which a radio signal stream may betransported over a packet-switched network in accordance with thisspecification;

FIG. 2 is a simplified functional block diagram illustrating additionaldetails that may be associated with example embodiments of thecommunication system;

FIG. 3 is a simplified functional block diagram that illustratesadditional details that may be associated with certain exampleembodiments the communication system;

FIG. 4 is a simplified functional block diagram that illustratesadditional details that may be associated with example embodiments of aninterworking function in the communication system;

FIG. 5 is a simplified stack diagram that illustrates potential detailsthat may be associated with a packet format in example embodiments ofthe communication system;

FIG. 6 is a simplified flow diagram illustrating potential operationsthat may be associated with example embodiments of the communicationsystem; and

FIG. 7 is a simplified flow diagram illustrating other potentialoperations that may be associated with example embodiments of thecommunication system.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

A method is provided in one example embodiment that includes receiving aradio signal stream and segmenting the radio signal stream into segments(e.g., blocks of data, pieces of information, bits of data, etc.). Thesegments may be packetized and transported in packets over a pseudowirein a packet-switched network. The radio signal stream can bereconstructed from the segments. In more particular embodiments, thepseudowire may be a multi-protocol label switching pseudowire or a layer2 tunneling protocol pseudowire, for example. In yet other specificexample embodiments, the radio signal stream may be received using acommon public radio interface or a femtocell application programminginterface. In yet other embodiments, the method may include parsing aparticular one of the segments for encapsulation into a packet payload.A control word is prepended to the particular one of the segments toidentify an order in which the segments can be reassembled by areconstructor provisioned along a downstream path in the packet-switchednetwork.

Example Embodiments

Turning to FIG. 1, FIG. 1 is a simplified block diagram of an exampleembodiment of a communication system 100 in which a radio signal may betransported over a packet-switched network in accordance with thisspecification. A radio equipment controller, such as radio equipmentcontroller (REC) 105 may be connected to radio equipment, such as radioequipment (RE) 110-119 through pseudowire connections, such aspseudowires 120 a-120 e. A backhaul communication path 130 interconnectsREC 105 with a service provider network 140. FIG. 1 further illustratesvarious topologies that may be associated with communication system 100,including a branch topology 150, a ring topology 160, a chain topology170, and a point-to-point topology 180. In certain embodiments, REC 105and REs 110-119 of communication system 100 may be representative of afronthaul wireless network topology in a distributed antennaarchitecture (DAA) in which REC 105 may control the operation ofantennas (e.g., REs 110-119) in such an architecture.

Before detailing the operations and the infrastructure of FIG. 1,certain contextual information is provided to offer an overview of thetypes of communications traversing communication system 100. Suchinformation is offered earnestly and for teaching purposes only and,therefore, should not be construed in any way to limit the broadapplications for the present disclosure. In some wireless communicationenvironments, specialized deployments may be needed to meet customercoverage requirements. For example, indoor spaces may not be conduciveto radio transmission, or a full macrocell deployment may not beeconomically justifiable in less populated areas. Other mobile ad hocnetworks (MANETs) may require a specialized deployment because ofenvironmental or QoS factors, for example. Generally, such specializedconnections are made using expensive, highly specialized optical orcoax-based, time-division multiplexing (TDM) architectures. As thecoverage radius of RE decreases, the expected traffic load from anyparticular RE site diminishes, the number of RE sites increases, andconventional point-to-point methods of interconnection becomeeconomically undesirable.

A distributed antenna architecture is an evolving alternative to suchconventional architectures. A distributed antenna architecture canprovide a network of spatially separated antenna nodes (e.g., REs110-119) connected to a common controller (e.g., REC 105) via atransport medium that provides wireless service within a geographic areaor structure. Radio signals to and from the common controller can bepassed through a system of multiple antennas. There are a number ofdifferent types of distributed antenna architectures, each with theirown characteristics. Passive DAA, for example, may be characterized bycombining radio signals with passive components such as filters,splitters, and couplers. Active DAA is another example in which radiosignals may be converted and distributed over fiber links. In yetanother example, hybrid DAA may combine features of passive DAA andactive DAA. Distributed antenna architectures may be particularlyadvantageous within a building or across a large urban area. In a largeurban area, for example, street-level DAA can provide a very efficientsolution for large urban regeneration projects that may require densecoverage. They can also be provided in other busy areas such as airportsor other mass transit hubs.

In some distributed antenna architectures, such as a cloud radio accessnetwork (CRAN) architecture, radio-processing functions may becentralized to resolve some power efficiency and resource utilizationconcerns with many intelligent radio/cell-site architectures. Ingeneral, a CRAN architecture provides a remote radio head (such as REs110-119) placed in close proximity to an antenna (or may be integratedwith an antenna). A remote radio head can translate a radio signal intoa digital bit stream, which can travel greater distances without loss.The digital signals from a remote radio head can be transmitted over afronthaul to a centralized baseband processing unit, which effectivelyshifts processing from the antenna and allows operators to pool andshare processor bandwidth across remote radio heads. A controller (e.g.,an REC, a base station controller, radio network controller, etc.) mayalso be co-located with the baseband processing to aggregate from cellsites and manage the radio access network.

The controller generally provides the network interface transport, radiobase station control and management, and digital baseband processing,whereas the remote radio head can provide the analog radio frequencyfunctions, such as filtering, modulation, frequency conversion, andamplification. The functional split between both parts is done in such away that a generic interface based on In-phase and Quadrature (IQ) datacan be defined.

CRAN can also reduce the number of cell sites, while increasing the basestation deployment density. By making a remote radio head an active unitcapable of converting from analog to digital, operators can placenumerous controllers in a single geographical point, while distributingradio heads according to the radio frequency (RF) plans. Activeelectronics of multiple cell sites can be centralized at one location,thereby reducing energy, real estate, and security costs. Radio headscan be mounted outdoor or indoor—on poles, sides of buildings oranywhere a power and a broadband connection exist, making installationless costly and easier. The remote radio heads become an intelligentantenna array, which not only can submit radio signals but can alsohandle the conversion between digital and analog data. A remote radiohead can also support multiple cellular generations (e.g., 2G, 3G, andLTE) eliminating the need for multiple antennas.

In an evolved UMTS Terrestrial Radio Access Network (E-UTRAN), forexample, the controller can provide access to the Evolved Packet Corefor the transport of user-plane and control-plane traffic via the S1interface, whereas a remote radio head can serve as the air interface tothe user equipment. In another example, a controller can provide accessto network entities (e.g. other base stations or an access servicenetwork-gateway (ASN-GW)) in a WiMAX network, whereas the radio head canserve as the air interface to the subscriber station/mobile subscriberstation (SS/MSS).

Common Public Radio Interface (CPRI) is a standard for transportingdigital radio signal streams (i.e., radio signals converted to a digitalbit stream) in a CRAN architecture over a link between a remote radiohead and a baseband processing unit. In more general CPRI terms, aremote radio head is commonly referred to as radio equipment (RE), and abaseband processing unit and/or controller is referred to as radioequipment control (REC). User-plane data, control and management (C&M)data, and synchronization signals can be exchanged between the REC andthe RE. Flows can be multiplexed onto a digital serial communicationline using appropriate layer 1 and layer 2 protocols. The differentinformation flows can access layer 2 via appropriate service accesspoints. CPRI may also be used as a link between two nodes in systemarchitectures supporting networking.

In general terms, CPRI provides a basic protocol hierarchy withfunctions running at Layer 1 (i.e., electrical or optical transmissionand time-division multiplexing (TDM)), and Layer 2. Layer 2 can includeIn-Phase and Quadrature (IQ) data, vendor-specific information,Ethernet, High-level Data Link Control (HDLC), L1 Inband Protocol,control and management (C&M) data, and synchronization. A basic layer 1frame of CPRI generally consists of sixteen words, the length of whichdepends on the CPRI line bit rate. The first word is used as a controlword, which is transmitted first. The control word can identify the typeof stream (e.g., user plane, C&M, synchronization) and the number ofsub-streams carried within the stream. Hence, the term “word” representsbroad terminology inclusive of any type of identifier, symbol,electronic object, signature, etc. that can be associated with a givenstream. The stream itself can represent any type of data beingpropagated between two points.

Other architectures, protocols, and interfaces may also provide fortransporting digital radio signal streams over a link between a remoteradio head and a baseband processing unit or controller. Femtocells, forexample, may be particularly advantageous in specialized spaces,including indoors. A common femtocell interface may be provided betweenradio frequency functions and baseband processing to enableinteroperability of components from different manufacturers. One suchstandard (commonly referred as the Femtocell Application ProgrammingInterface or FAPI) has been proposed that includes a securitycoprocessor interface, a service discovery interface, a GPS interface, anetwork listen results interface, a PHY mode control interface, aciphering coprocessor interface, a main data path interface, and ascheduler interface.

The Open Base Station Architecture Initiative (OBSAI) is another exampleof a family of specifications that provides the architecture, functiondescriptions, and minimum requirements for integration of a set ofcommon modules into a base transceiver station (BTS). As a minimum, theBTS can be configured from a set of common modules in order to supportone or more current or future wireless network access standards. Thetechnical requirements contained in the OBSAI family of specificationsform an interface specification to ensure compatibility andinteroperability among and between the set of common modules.

Yet other examples include a standard from VME International TradeAssociation (VITA 49) and the Open Radio Equipment Interface (OREI).VITA 49 is an interconnect standard for passing intermediate frequency(IF) data between analog front-ends and digital signal processorsubsystems in a digital, link-agnostic format. OREI is defined by theIndustry Specification Group as a method for standardizing thecommunications interface of distributed radio equipment for mobilecommunication networks. In general, OREI covers those layers of anetwork stack required to enable interoperability, and may be built onother publicly available specifications, including CPRI.

While distributed antenna architectures and radio interfaces may providemany advantages and benefits for fronthaul, the radio interfacesthemselves are generally TDM-based Layer 1/Layer 2 protocols.Consequently, implementing such an architecture for fronthaulapplications presents significant challenges for integration withpacket-based backhaul deployments.

In accordance with embodiments described herein, communication system100 can overcome these challenges and others by providing a system andmethod for transporting radio signal streams over a packet-switchednetwork. More particularly, communication system 100 may provide apseudowire for transporting a digital radio signal stream between aremote radio head and a baseband processing unit (e.g., usingMulti-Protocol Label Switching (MPLS) or Layer 2 Tunneling Protocolversion 3 (L2TPv3)).

A pseudowire is an emulation of a point-to-point connection over apacket-switched network (PSN). A pseudowire emulates the operation of a“transparent wire” carrying the service. The service being carried overthe “transparent wire” may be CPRI, FAPI, OBSAI, VITA 49, OREI,asynchronous transfer mode (ATM), frame relay, Ethernet, TDM, or anyother connection-oriented synchronous or plesiochronous links. Anexample of a pseudowire is described in Request for Comments (RFC) 3985published by the Internet Engineering Task Force (IETF). A pseudowiremay operate over many types of PSNs, including MPLS or L2TPv3 over IP,as well as a user datagram protocol (UDP) over IPv4 or IPv6, MPLS,L2TPv3 over IP, and Ethernet, for example.

In broad terms, MPLS is a routing protocol. More particularly, MPLS isalso a highly scalable, protocol agnostic, data-carrying mechanism. Inan MPLS network, data packets can be assigned labels. Packet-forwardingdecisions can be made solely on the contents of this label, without theneed to examine the packet itself. End-to-end circuits can be createdacross any type of transport medium, using any protocol. MPLS caneliminate dependence on a particular networking model data link layertechnology and eliminate the need for multiple layer 2 networks tosatisfy different types of traffic. A label distribution protocol (LDP),such as described in IETF RFC 5036, and/or a resource reservationprotocol for traffic engineering (RSVP-TE), such as described in IETFRFC 3209, may be used for pseudowire setup. Moreover, MPLS can alsointegrate operations, administration, and management (OAM) with thepseudowire, which may be particularly advantageous for diagnosing remoteconnections end- to-end.

MPLS operates at a layer that is generally considered to lie betweentraditional definitions of layer 2 (data link layer) and layer 3(network layer), and thus is often referred to as a “layer 2.5”protocol. It can provide a unified data-carrying service for bothcircuit-based clients and packet-switching clients that provide adatagram service model. It can be used to carry many different kinds oftraffic, including Internet Protocol (IP) packets, as well as nativeATM, synchronous optical networking (SONET), and Ethernet frames.

L2TP is an encapsulation technique that allows packets to be transportedbetween a pair of endpoints inside IP packets. L2TPv3 is an IETFstandard (see RFC 3931) related to L2TP that can be used as analternative to MPLS for encapsulation of multiprotocol Layer 2communications traffic over IP networks. Like L2TP, L2TPv3 provides apseudowire service, but scaled to fit carrier requirements. L2TPv3 canalso provide end-to-end encryption, which avoids the need to separatelyencrypt each radio signal stream.

In certain example embodiments, a wireless access point may beconfigured as a remote radio head (e.g., an RE) in a distributed antennaarchitecture, such as CRAN, using various radio interface specificationsto transport digital radio signal streams over a pseudowire between thewireless access point and radio equipment control (e.g., a basebandprocessing unit or controller). A signal stream does not necessarilyhave channelization, framing, or other timing structures, such that itcan include unstructured synchronous serial data, as well as structuredsynchronous data. Thus, for example, wireless access points such as REs110-119 in communication system 100 may receive radio signal streamsfrom endpoints and transport them to a centralized baseband-processingunit or controller, such as REC 105, using CPRI over an MPLS or L2TPv3pseudowire. Such endpoints may be associated with subscribers, clients,or customers wishing to access communication system 100, for example.

The term “endpoint” or “node” may be inclusive of devices used toinitiate a communication, such as a computer, any type of userequipment, any type of mobile station, any type of smart phone, apersonal digital assistant (PDA), a laptop or electronic notebook, acellular telephone, an iPhone, an iPad, a Google Android phone, anInternet Protocol (IP) phone, or any other device, component, element,or object capable of initiating voice, audio, or data exchanges withincommunication system 100. Endpoints may also be inclusive of a suitableinterface to the human user, such as a microphone, a display, or akeyboard or other terminal equipment.

Endpoints may also be any device that seeks to initiate a communicationon behalf of another entity or element, such as a program, a database,or any other component, device, element, or object capable of initiatinga voice or a data exchange within communication system 100. Data, asused herein, refers to any type of numeric, voice, or script data, orany type of source or object code, or any other suitable information inany appropriate format that may be communicated from one point toanother.

FIG. 2 is a simplified functional block diagram 200 illustratingadditional details that may be associated with example embodiments ofcommunication system 100. In FIG. 2, REC 105 is connected to RE 110through pseudowire 120 a. REC 105 may also be connected to other REs,such as REs 114-119 through a PSN 205. An interworking function (IWF)210 and an IWF 220 can encapsulate and decapsulate radio signal streamsto/from REC 105 and RE 110, respectively, while simultaneouslyencapsulating and decapsulating packetized data to/from PSN 205. IWFs210-220 may be coupled with or integral to REC 105 and RE 110,respectively.

FIG. 3 is a simplified functional block diagram 300 that illustratesadditional details that may be associated with certain exampleembodiments of communication system 100. More particularly, FIG. 3illustrates additional details that may be associated with a pseudowiresuch as pseudowire 120 a in communication system 100. In thisembodiment, pseudowire 120 a may comprise a pair of IWFs 310-320 and PSN205 to create a bidirectional virtual circuit. A PSN-bound IWFT 330 maycreate a tunnel 351 (e.g., an MPLS or a L2TPv3 tunnel) through PSN 205to a stream-bound IWFT 390. A PSN-bound IWFT 380 may independentlycreate a tunnel 352 through PSN 205 to a stream-bound IWFT 340. In someembodiments, PSN-bound IWFT 330 may be connected to an ingress router ofPSN 205, while in other example embodiments IWFT 330 may be integratedwith (or coupled to) radio equipment, such as REC 105. IWFT 340 may beconnected to an egress router of PSN 205, or may also be integrated with(or coupled to) radio equipment, for example. PSN-bound IWFT 380 mayalso be connected to an ingress router of PSN 205, or may be integratedwith (or coupled to) radio equipment, such as RE 110. IWFT 390 may beconnected to an egress router of PSN 205, or may be integrated with (orcoupled to) radio equipment.

In some example implementations, REC 105, REs 110-119, IWFs 210-220,and/or other elements of communication system 100 are network elements,which are meant to encompass network appliances, servers, routers,switches, gateways, bridges, load balancers, firewalls, base stations,access points, processors, modules, or any other suitable device,component, element, or object operable to exchange information in anetwork environment. Moreover, the network elements may include anysuitable hardware, software, components, modules, interfaces, or objectsthat facilitate the operations thereof. This may be inclusive ofappropriate algorithms and communication protocols that allow for theeffective exchange of data or information.

In regard to the internal structure associated with elements ofcommunication system 100, REC 105, REs 110-119, IWFs 210-220, and/orother elements can include memory elements for storing information to beused in the operations outlined herein. Each of REC 105, REs 110-119,IWFs 210-220, and/or other elements may keep information in any suitablememory element (e.g., random access memory (RAM), read-only memory(ROM), erasable programmable ROM (EPROM), electrically erasableprogrammable ROM (EEPROM), application specific integrated circuit(ASIC), etc.), software, hardware, or in any other suitable component,device, element, or object where appropriate and based on particularneeds. Any of the memory items discussed herein should be construed asbeing encompassed within the broad term “memory element.” Theinformation being used, tracked, sent, or received by REC 105, REs110-119, IWFs 210-220, and/or other elements could be provided in anydatabase, register, queue, table, cache, control list, or other storagestructure, all of which can be referenced at any suitable timeframe. Anysuch storage options may be included within the broad term “memoryelement” as used herein.

In certain example implementations, the functions outlined herein may beimplemented by logic encoded in one or more tangible media (e.g.,embedded logic provided in an ASIC, digital signal processor (DSP)instructions, software (potentially inclusive of object code and sourcecode) to be executed by a processor, or other similar machine, etc.),which may be inclusive of non-transitory media. This includes the memoryelements being able to store software, logic, code, or processorinstructions that are executed to carry out the activities describedherein.

In one example implementation, REC 105, REs 110-119, IWFs 210-220,and/or other elements may include firmware and/or software modules toachieve, or to foster, operations as outlined herein. In otherembodiments, such operations may be carried out by hardware, implementedexternally to these elements, or included in some other network deviceto achieve the intended functionality. Alternatively, these elements mayinclude software (or reciprocating software) that can coordinate inorder to achieve the operations, as outlined herein. In still otherembodiments, one or all of these devices may include any suitablealgorithms, hardware, software, components, modules, interfaces, orobjects that facilitate the operations thereof.

Additionally, REC 105, REs 110-119, IWFs 210-220, and/or other elementsmay include a processor that can execute software or an algorithm toperform activities as discussed herein. A processor can execute any typeof instructions associated with the data to achieve the operationsdetailed herein. In one example, the activities outlined herein may beimplemented with fixed logic or programmable logic (e.g.,software/computer instructions executed by a processor) and the elementsidentified herein could be some type of a programmable processor,programmable digital logic (e.g., a field programmable gate array(FPGA), an EPROM, an EEPROM) or an ASIC that includes digital logic,software, code, electronic instructions, or any suitable combinationthereof. Any of the potential processing elements, modules, and machinesdescribed herein should be construed as being encompassed within thebroad term “processor.”

FIG. 4 is a simplified functional block diagram 400 that illustratesadditional details that may be associated with example embodiments of anIWF in communication system 100. A bi-directional IWF 402 includes aprocessor 404 and a memory element 406, and may also include additionalhardware, firmware, and/or software elements, such as a stream interface408, a PSN-bound IWFT 410, a stream-bound IWFT 412, a communications andcontrol interface 414, and a PSN interface 416. Hence, appropriatesoftware, firmware, and/or hardware may be provisioned in IWF 405 tofacilitate the activities discussed herein. IWFTs 410-412 may shareresources in some embodiments, including processor 404 and memoryelement 406, and may have a common communications and control interface(e.g., communications and control interface 414). In other exampleembodiments, IWFTs 410-412 may have any combination of dedicatedelements. IWF 402 may interface with a PSN such as PSN 205.

In this example, IWFT 410 includes a stream segmentor 418, a streamadapter 420, a control word prefixer 422, and an encapsulator 424operating in the ingress direction of PSN 205. Segmentor 418 can parsean incoming contiguous stream into finite sized data segments suitablein size to be encapsulated into a packet payload. In this exampleembodiment, stream adapter 420 may provide data to assist in timingrecovery and recovery from packet loss and to ensure proper transfer ofstream signaling. Control word prefixer 422 may prepend to a segment(post adaption) a control word that helps identify the order in whichsegments should be reassembled by a reconstructor at the other end of aunidirectional downstream path. Encapsulator 424 may encapsulate thepayload data with a network header, such as an IP header, and apseudowire header, such as an MPLS or L2TPv3 header.

IWFT 420 may include a decapsulator 426, a control word analyzer andstripper 428, a stream adaption analyzer 430, and a reconstructor 432operating in the egress direction of PSN 205. Decapsulator 426 may beused to analyze and remove network and pseudowire headers (e.g., IP/MPLSor IP/L2TPv3 headers). Control word analyzer and stripper 428 can stripcontrol words and reorder the arriving stream payloads so they can beappropriately ordered (e.g., into a contiguous stream). Stream adaptionanalyzer 430 may analyze and strip adaption data so that the propertiming and packet loss recovery modes of the stream can be implemented.Reconstructor 432 can reconstruct the stripped and ordered payloads intoa contiguous stream.

FIG. 5 is a simplified stack diagram 500 that illustrates details thatmay be associated with a packet format in example embodiments ofcommunication system 100. Packet 502 generally includes PSN-specificheaders and a stream payload. PSN-specific headers provide informationfor forwarding packet 502 from a PSN-bound IWFT to a stream-bound IWFT.PSN-specific headers may be headers for UDP/IP, L2TPv3/IP, MPLS, orlayer 2 Ethernet, for example. In the example of packet 502, thePSN-specific headers include network layer headers 504 (e.g., IPheaders) and pseudowire headers 506 (e.g., MPLS or L2TPv3). An IWF maysimultaneously support multiple pseudowires, and the IWF may maintaincontext information for each pseudowire. Pseudowires can bedifferentiated based on pseudowire labels, which can be carried inpseudowire headers 506, for example. Stream data may be modified in astream payload 508, which may include a stream adaption 510, a controlword 512, and a stream segment 514, for example.

FIG. 6 is a simplified flow diagram 600 illustrating potentialoperations that may be associated with example embodiments ofcommunication system 100. In some embodiments, these operations may beassociated with a PSN-bound IWFT (e.g., IWFT 410) in a radio element,such as REC 105 or RE 110, for example. In other embodiments suchoperations may be implemented in other network elements, such as arouter, switch, etc., or as an independent network appliance. In otherembodiments the operations may be distributed among various networkelements.

A radio signal stream may be received at 602 and parsed into segments at604, suitable in size to be encapsulated into a packet payload. Packetloss and timing recovery data may be integrated into the segments at606. A control word may be prepended to a segment at 608, which canidentify the order in which segments should be reassembled by areconstructor at the other end of a downstream path. At 610, segmentsmay be encapsulated with a network header, such as an IP header, and apseudowire header, such as an MPLS or L2TPv3 header. The packetizedsegments may then be transported over a PSN at 612, to another radioelement, for example.

FIG. 7 is a simplified flow diagram 700 illustrating potentialoperations that may be associated with example embodiments ofcommunication system 100. In some embodiments, these operations may beassociated with a stream-bound IWFT (e.g., IWFT 412) in a radio element,such as REC 105 or RE 110, for example. In other embodiments suchoperations may be implemented in other network elements, such as arouter, switch, etc., or as an independent network appliance. In otherembodiments the operations may be distributed among various networkelements.

A packet carrying a radio signal stream segment may be received at 702.Network and pseudowire headers may be analyzed and removed at 704.Control words can be stripped and payloads reordered at 706 so they canbe appropriately ordered into a contiguous stream. Adaption data may beanalyzed and stripped at 708 so that the proper timing and packet lossrecovery modes of the stream can be implemented. The stripped andordered payloads can be reconstructed into a contiguous stream at 710and transmitted at 712.

Embodiments of communication system 100 may provide significantadvantages, some of which have already been discussed. For example,embodiments of communication system 100 can be deployed as a fronthaulusing networking elements common in IP backhaul networks. Communicationsystem 100 can support geographical distribution of controllers andradio equipment, and allow operators to deploy distributed antennaarchitectures over PSNs, while reducing manufacturing and deploymentexpense. Further, communication system 100 may also allow small cells tobe tightly integrated into mobile carrier networks, with a commoncloud-based signal processing system.

Note that with the examples provided above, as well as numerous otherexamples provided herein, interaction may be described in terms of two,three, or four network elements. However, this has been done forpurposes of clarity and example only. In certain cases, it may be easierto describe one or more of the functionalities of a given set of flowsby only referencing a limited number of network elements. It should beappreciated that communication system 100 (and its teachings) arereadily scalable and can accommodate a large number of components, aswell as more complicated/sophisticated arrangements and configurations.Accordingly, the examples provided should not limit the scope or inhibitthe broad teachings of communication system 100 as potentially appliedto a myriad of other architectures. Additionally, although describedwith reference to particular scenarios, where a particular module, suchas a participation level module, is provided within a network element,these modules can be provided externally, or consolidated and/orcombined in any suitable fashion. In certain instances, such modules maybe provided in a single proprietary unit.

It is also important to note that the operations in the appendeddiagrams illustrate only some of the possible signaling scenarios andpatterns that may be executed by, or within, communication system 100.Some of these operations may be deleted or removed where appropriate, orthese operations may be modified or changed considerably withoutdeparting from the scope of teachings provided herein. In addition, anumber of these operations have been described as being executedconcurrently with, or in parallel to, one or more additional operations.However, the timing of these operations may be altered considerably. Thepreceding operational flows have been offered for purposes of exampleand discussion. Substantial flexibility is provided by communicationsystem 100 in that any suitable arrangements, chronologies,configurations, and timing mechanisms may be provided without departingfrom the teachings provided herein.

Numerous other changes, substitutions, variations, alterations, andmodifications may be ascertained to one skilled in the art and it isintended that the present disclosure encompass all such changes,substitutions, variations, alterations, and modifications as fallingwithin the scope of the appended claims. In order to assist the UnitedStates Patent and Trademark Office (USPTO) and, additionally, anyreaders of any patent issued on this application in interpreting theclaims appended hereto, Applicant wishes to note that the Applicant: (a)does not intend any of the appended claims to invoke paragraph six (6)of 35 U.S.C. section 112 as it exists on the date of the filing hereofunless the words “means for” or “step for” are specifically used in theparticular claims; and (b) does not intend, by any statement in thespecification, to limit this disclosure in any way that is not otherwisereflected in the appended claims.

What is claimed is:
 1. A method, comprising: receiving a radio signalstream; segmenting the radio signal stream into segments; transportingthe segments in packets over a pseudowire in a packet-switched network;and reconstructing the radio signal stream from the segments.
 2. Themethod of claim 1, wherein the pseudowire is a multi-protocol labelswitching pseudowire.
 3. The method of claim 1, wherein the pseudowireis a layer 2 tunneling protocol pseudowire.
 4. The method of claim 1,wherein the radio signal stream is received using a common public radiointerface.
 5. The method of claim 1, wherein the radio signal stream isreceived using a femtocell application programming interface.
 6. Themethod of claim 1, wherein a selected one of the segments includespacket loss, timing recovery data, and a control word identifying anorder in which the segments can be reassembled.
 7. The method of claim1, further comprising: parsing a particular one of the segments forencapsulation into a packet payload, wherein a control word is prependedto the particular one of the segments to identify an order in which thesegments can be reassembled by a reconstructor provisioned along adownstream path in the packet-switched network.
 8. Logic encoded in oneor more non-transitory media that includes code for execution and whenexecuted by one or more processors is operable to perform operationscomprising: receiving a radio signal stream; segmenting the radio signalstream into segments; transporting the segments in packets over apseudowire in a packet-switched network; and reconstructing the radiosignal stream from the segments.
 9. The encoded logic of claim 8,wherein the pseudowire is a multi-protocol label switching pseudowire.10. The encoded logic of claim 8, wherein the pseudowire is a layer 2tunneling protocol pseudowire.
 11. The encoded logic of claim 8, whereinthe radio signal stream is received using a common public radiointerface.
 12. The encoded logic of claim 8, wherein the radio signalstream is received using a femtocell application programming interface.13. The encoded logic of claim 8, wherein a selected one of the segmentsincludes packet loss, timing recovery data, and a control wordidentifying an order in which the segments can be reassembled.
 14. Theencoded logic of claim 8, the operations further comprising: parsing aparticular one of the segments for encapsulation into a packet payload,wherein a control word is prepended to the particular one of thesegments to identify an order in which the segments can be reassembledby a reconstructor provisioned along a downstream path in thepacket-switched network.
 15. An apparatus, comprising: a firsttranscoder; a second transcoder; and one or more processors operable toexecute instructions associated with the first transcoder and the secondtranscoder such that the apparatus is configured to: receive a firstradio signal stream through a stream interface; segment the first radiosignal stream into first segments; transport the first segments througha packet-switched network interface in first packets over a firstpseudowire in a packet-switched network; receive second segments insecond packets through the packet-switched network interface over asecond pseudowire in the packet-switched network; reconstruct a secondradio signal stream from the second segments; and transparent the secondradio signal stream as a contiguous stream through the stream interface.16. The apparatus of claim 15, wherein at least one of the first andsecond pseudowires is a multi-protocol label switching pseudowire. 17.The apparatus of claim 15, wherein at least one of the first and secondpseudowires is a layer 2 tunneling protocol pseudowire.
 18. Theapparatus of claim 15, wherein at least one of the first and secondradio signal streams is received using a common public radio interface.19. The apparatus of claim 15, wherein at least one of the first andsecond radio signal streams is received using a femtocell applicationprogramming interface.
 20. The apparatus of claim 15, wherein theapparatus is further configured to: parse a particular one of thesegments for encapsulation into a packet payload, wherein a control wordis prepended to the particular one of the segments to identify an orderin which the segments can be reassembled by a reconstructor provisionedalong a downstream path in the packet-switched network.